fix a minor fixme. When building with SL and later tools, the ".eh" symbols

fix a minor fixme.  When building with SL and later tools, the ".eh" symbols
don't need to be exported from the .o files.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78892 91177308-0d34-0410-b5e6-96231b3b80d8